Refrigerating apparatus



Dec. 23, 1941- w. J. HARVEY REFRIGERATING APPARATUS Filed March 8, 1939INVENTOR i M ATTORNEY ceiver.

Patented Dec. 23, 1941 REFRIGERATING APPARATUS William J. Harvey,Detroit, Mich., assignor t D troit Lubricator Company, Detroit, Mich.,acorporation of Michigan 14 Claims.

My invention relates to new and usei'ul improvements in refrigeratingapparatus, and more particularly to means for controlling the operationof the same.

In installations of refrigerating apparatus it frequently happens,particularly in commercial installations, that the compressor orcondenser, or both, are positionedin an unheated space or are subject toatmospheric temperature. When the compressor is so situated it willoccur, under certain conditions, that the refrigerant medium willdistill over from the evaporator into the compressor crankcase duringthe off" periods of compressor operation, with the result that uponstarting up of the compressor, oil will be pumped out of the crankcaseand discharged with the refrigerant, resulting in serious damage to thecompressor. In a pressure control system, should the compressor besufficiently cooled, all of the refrigerant might distill over into thecompressor, and since the pressure in the refrigerating system would notbe great enough to start compressoroperation, refrigeration would ceaseentirely. Where the condenser is so situated, it may happen that thepressure of the refrigerant medium, when ambient temperature is low,will drop to a point such that the liquid refrigerant medium will notimmediately be fed to the evaporator upon starting-up of the compressor,and under some conditions the compressor might not be able to buildsufficient "high side pressure to feed refrigerant to the evaporator atall. Also, when the condenser is so situated and is water cooled, thecooling water which remains in the condenser during the "oif period ofcompressor operation may freeze, thereby mining the condenser. It istherefore one of the objects of my invention to provide means by whichone or more or all of the foregoing disadvantages may be overcome.

In commercial installations of walk-in or meat box refrigerators it iscommon practice to install the compressor and condenser-receiver in aconvenient place, adjacent the refrigerator, and in such an installationthe ambient temperature affecting the heat leakage of the refrigeratoris also affecting the compressor and condenser-re- In suchinstallations, as the ambient temperature becomes low, the heat leakageto the interior of the refrigerator decreases and the compressor isrequired to run for less time and the evaporator approaches and may evenassume the air temperature within therefrigerator so that aircirculation is no longer maintained by the evaporator. Upon theoccurrence of such an tion will be apparent therefore to ApplicationMarch 8, 1939, Serial No. 260,601

event the air becomes very humid so that the moisture therein condensesout and deposits on the meats or other perishables stored in therefrigerator thereby causing sliming of the stored materials. A furtherobject of my invention is provide means by which a sufliciently frequentcycling of a refrigerating system will be accomplished to overcome thiscondition of deleterious condensation of moisture.

Another object of my invention is to provide a unit structure which iscompact, economical of manufacture and easy to install.

Further objects and advantages of my invenfrom the followingspecification and the appended claims.

The invention consists in the novel apparatus and the cooperativerelation of the parts of the system.

In the accompanying drawing, to be taken as a part of thisspecification, I have fully and clearly illustrated my invention, inwhich drawin Figure 1 is a diagrammatic view showing a refrigeratingapparatus having means forcontrol-i ling the operation of the same inaccordance with my invention, and

Fig. 2 is a modification of my invention showing an alternative meansfor controlling operation of my apparatus.

Referring to the drawing by characters of reference the numeral Idesignates a refrigerating compressor driven by a motor 2 by means of abelt 3. The motor! is supplied with electrical energy from a source ofsupply through main lead wires 4, 5. Connected in series with the leadwire 4 is a control apparatus generally designated 6,.which operates tostart and stop the motor 2. Upon operation of the compressor lrefrigerant vapor is discharged therefrom through a conduit I into acondenser-receiver 8 where it is condensed into a liquid. The condensedliquid refrigerant flows from the condenser-receiver i through a conduit9 to an evaporator, generally designated I 0, walk-in cooler or meatbox, generally designated H. A conduit or suction line I2 conveys thevaporous refrigerant from the evaporator it to the inlet of.therefrigerant compressor I. The flow of liquid refrigerant'from the liquidconduit 8 to the evaporator I8 is controlled by means of an expansionvalve l3 interposed in the conduit 9 adjacent the inlet to theevaporator l0. Secured to the return line l2 adjacent the outlet of theevaporator I0 is a temperature sensitive bulb H communicativelyconnected by means of located within and for cooling a' the usualcapillary tube l to the thermostatic power element or the expansionvalve ll so that the valve is operable to maintain liquid refrigerantthroughout the entire length or the evaporator I0.

The control apparatus 6 comprises a casing l5 having side walls l1, l8,9. top wall I! and a bottom wall 20. A pressure sensitive power element22 is secured to the sidewall l8 by means of screws 2| and preferablycomprises a hollow, cup-shaped member 24 having its open end adjacentthe wall I8 and housing a pressure sensitive bellows element 25. Anannular ring 26 is sealed to the inner wall of the member 24 adjacentits open end and carries one end or the bellows element 25. The otherend of the bellows element 25 extends toward the bottom wall 25 of thecup-shaped member 24 and is sealed to a rigid, movable end wall 21. Themember 24, bellows element 25, ring 25, and wall 21 cooperate to form asealed pressure sensitive chamber 28 communicatively connected with thesuction line l2 through a conduit 29. One end of a horizontallyextending thrust member 80 is secured to the end wall 21 and the otherend extends through an aperture in the casing side wall 18 into theinterior of the casing Ii, and terminotes in a cone-shaped portion whichengages a socket portion II on a vertically extending arm 82 of a. bellcrank lever 38 pivotally secured, as at 54, to the casing 18. The otheror horizontal arm 85 of the bell crank lever 83 is spaced from and isparallel to the bottom wall 20 and projects toward the side wall Il.

Secured to the side wall l1 and in substantially horizontal alignmentwith the thrust member 88 is one end of a threaded member 35". The

to fluid pressure in the condenser-receiver 8. A thrust member 59 hasone end secured to the plate member 56 and its other end extendingtoward and operable to engage the top wall IQ of the casing l6 to limitcollapsing movement of the bellows 55. A lever member 60 is pivotallycarried by the spacer member 52, as at SI, for rotational movement, andhas one end 62 received within an aperture 63 in the lower end of thethrust member 59. The other end 64 of the lever member 60.pivotallycarries the upper end 55 o! a thrust rod 66. The thrust rod 66 extendsthrough an aperture in the top wall 18 and into the casing l6 so thatthe lower end 51 is operable to engage the upper side of and to move theswitch arm member 45 into circuit closed position upon a predeterminedlow pressure in the power element 5|. Carried by the casing 15 andextending above the wall I! thereof is an L-shaped member 68 having ahorizontal portion 59 overlying the lever member 60. A verticallyextending adjustment member 10 having a slotted head-portion H isscrew-threaded in the horizontal portion 6] and has a lower end portion12 abutting a plate-like spring abutment member 18. A helical coiladjusting spring 14 is held under compression between the plate 13 and aspring abutting plate 15 having a downwardly other end of the member 35*extends toward the abutment member 35 and a plate-like abutment member"having a portion 39 received within a socket 40 in the verticallyextending arm 52 of the bell crank lever 88, and exerts a force opposingmovement of the arm 32 by the power element 22, due to increase inpressure within the chamber 28. A thrust rod 42 has. one end pivotallyconnected, as at 48, to the arm 85 and has its other end pivotallysecured, as at 44, to a switch arm member 45. The switch arm member 45is fulcrumed, as at 45, on the wall IT. A contact member 41 carried bythe switch ann member 45 cooperates with a stationary contact member 48to make and break the electrical circuit through the lead wire 4 to themotor 2.

A permanent, U-shaped magnet 49 secured to the casing it, as by clips50, cooperates with the witch and member 45 to cause a quick making andbreaking of the circuit by the contact memm su. a.

I A second pressure sensitive power element 5| 7 is secured to butspaced from the top wall l9 of easing I! by means of a hollow spacermem- ,end oi'the bellows extends within the memher" and is sealed by arigid plate'member 56.

The members 58, 54 and 58 and the bellows 55 cooperate to form apressure sensitive chamber I! which is communicatively connected bymeans of a'conduit 58 to the compressor discharge conduit'l so that thepower element 5| is responsive extending portion 16 engaging the levermember 68. The member HI and spring 14 cooperate to regulate thepredetermined low pressure at which the power element 5| operates torotate the lever member 60 so that the switch arm member 45 is moved tocircuit closed position.

The condenser-receiver 8 contains a water cooled condensing coil havingan inlet 8| and an outlet 82. inlet 8l'of the condensing coil 80 from asuitable source of supply (not shown). A pressure sensitive valve,generally designated 83, is secured to the outlet 82 and controls theflow of cooling water to the condenser-receiver coil 80. A con-- duit 84has one end 85 secured to the top end wall of and in communication withthe condenser-receiver 8 and its other end 88 secured to and incommunication with the power element 81 of the valve 83. Fluid pressureis thereby communicated from the interior of the condenser-receiver 8 tothe power element 81 to contgtoil flow of cooling water through thecooling coil In Fig. 2 in which like parts are designated by likenumerals, I have shown a bulb' member I00 located within thecondenser-receiver 8 and sensitive to the temperature of the refrigerantmedium contained in the condenser-receiver. The bulb member I00 containsa quantity of volatile, temperature sensitive liquid and iscommunicatively connected bymeans of a capillary tube III to the powerelement SI of the control apparatus 6, so that the temperature, andconsequently the pressure of the refrigerant within thecondenser-receiver 8 is reflected by means of the pressure in the closedsystem comprising the bulb I00, capillary tube llll and power element5|.

The operation of my apparatus is as follows: Liquid refrigerant of asuitable nature flows from the condenser-receiver-8 through the liquidconduit 8 to the expansionvalve, I} where it flows into the evaporatori0, and its flow is so regulated by the'valve I S'that during operationof the compressor the entire length oi the evaporator containsevaporating liquid refrigerant but none passes into the conduit I2. Thevaporous Cooling water is supplied to the,

spring 31 and the power element 22.

refrigerant flows from the evaporator ll through the conduit I! to theinlet of the compressor l where it is compressed by the compressor anddischarged through conduit 1 to the condenserreceiver 8 where the highpressure, vaporous refrigerant is condensed by means of the cooling coil80 back to a liquid. Preferably the valve '3 acts to control the flow ofcooling water through the cooling coil 80 in response to fluid pressurein the condenser-receiver 8 to maintain a predetermined, substantiallyconstant condensing temperature of the refrigerant during periods ofcompressor operation. The control apparatus -6 normally operates tomaintain the pressure in the suction line I! between predeterminedconstant pressure limits, operating to start the compressor uponincrease to a predetermined maximum pressure and to stop the operationof the same upon a predetermined low pressure so that the evaporatoriii-maintained at a substantially constant temperature. It is to beunderstood however that operation of the compressor 1 could becontrolled by any other suitable means responsive either to thetemperature of the evaporator II or to the temperature of the meatboxil.

As the temperature of the space surrounding the condenser-receiver 8 andthe compressor I becomes lower, the pressure and temperature of therefrigerant within the condenser-receiver 8 will decrease and upon adecrease thereof to a predetermined minimum pressure or temperature thepower element BI and spring 14 cooperate to rotate the lever arm 80 sothat the thrust rod 65 engages and rotates the switch arm member" toplace contact members 41, ll in closed circuit position. This completesthe electrical circuit through lead wires 4, and the motor 2 andoperation of the compressor l will ensue regardless of the pressurewithin the suction line i2. Upon the attainment ofa predeterminedconstant pressure above the predetermined low pressure in thecondenser-receiver 8, the power element 5| and spring 14 cooperate torotate the lever member 60 in a clockwise direction to release theswitch arm member. 45 for normal operation under the influence of theThemedetermined pressures at which the power element 5| cooperates toopen and close the circuit to the motor 2 may be varied by means of theadjustment member 10, and the predetermined pressure at which the powerelement 22 cooperates to open and close the circuit may be varied by theadjustment of the member 36.

The predetermined minimum pressure at which the power element I is setto move the contact members I1,- I to circuit making posi-- tion ispreferably above the normal pressure at which the power element 22 isoperable to cause operation of the compressor so that the temperature ofthe compressor l and the condenserreceiver 8 will be maintained abovethe temperature at which the refrigerant from the evaporator acts todistill over into the crankcase to cause slugging or pumping of oiluponstarting of'the compressor. I also maintain the compressor I abovethetemperature at which the liquid might distill into the crankcase of thecompressor l and. remain there at a pressure below the cut-in pressureof the power element 1! so that refrigeration within the meat box I Iwill cease. By adjusting the predetermined pressure at which the powerelement 5| acts to move the switch arm member 4! into circuit closed po--compressor at frequent intervals so as to maintain air circulation bythe evaporator In in the meat box I! and also maintain the relativehumidity therein below that which will cause condensation upon thestored food products.

The operation of Fig. 2 is similar to that of I Fig. 1 except thatoperation of the power element 5| is controlled by means of thetemperature within the condenser-receiver.8 as reflected by the bulb I00rather than directly by the fluid pressure of the refrigerant within thecondenserreceiver. It is to be understood that pressures andtemperatures may be used interchangeably as any temperature may bereflected as pressure in accordance with the teachings of the disclosureof Fig. 2.

It may now be seen that I have invented a new and'improved means for arefrigerating systern whereby I am able to prevent freezing of thecondenser water in a water cooled condenser regardless of the ambienttemperature. By utilizing my invention the distillation of therefrigerant from the evaporator into the compressor crankcase isprevented and also suflicient pressures and temperatures will bemaintained at the compressor and condenser-receiver at all ambienttemperatures to force the liquid refrigerant from the liquid receiver tothe evaporator, and to cause frequent compressor operation. Furthermore,by utilizing my invention I auto-- matically change the operation of therefrigerating system from summer operation to winter operation withoutthe necessity of manually adjusting the controls, and this automaticchange in operation automatically prevents the formaticnof slime whensuch perishables as meat are stored in the refrigerated space.

What I claim and desire to secure by Letters Patent of the United Statesis:

1. In a refrigerating system having a liquidcooled condenser, means tosupply warm refrigerant medium to the condenser, and means operable torender said supply means effective upon a decrease of condensertemperature to a temperature below normal condenser operatingtemperature but above a subnormal condenser temperature which wouldcause freezing of the condenser liquid thereby to avoid deleteriouseffects on the condenser.

2. In a refrigerating system having a condenser adapted for condensing arefrigerant medium, means for supplying the refrigerant medium to thecondenser, means controlling operation of said supply means, and meansoperable to actuate said controlling means at a refrigerant mediumcondenser pressure below normal condenser'operating pressure to startthe supplying of refrigerant medium to the condenser.

3. In a refrigerating system having a condenseradapted for condensing arefrigerant medium, means for supplying the refrigerant medium to thecondenser, means controlling operation of said supply means, and meansto actuate said controlling means upon decrease of condenser pressuresubstantially to a pressure which would render the system inoperative.

4. In a cyclically. operating refrigerating sys- I tem having acondenser for condensing a gaseous refrigerant medium, means operable tosupply the gaseous refrigerant medium to said condenser and renderedeffective at spaced intervals, and means operable upon a predetermineddecrease in temperature of said condenser below normal condenseroperating temperature to render said 5 means effective intermediate saidintervals of and means operable intermediate said intervals of operationand upon occurrence of a predeter- 'mined condenser pressure toestablish an increased condenser pressure.

6. In a cyclically operating refrigerating system having a condenser,means operable to supply gaseous refrigerant medium to said condenserand rendered effective at spaced intervals, and means operableintermediate said intervals of operation and upon occurrence of apredetermined condenser pressure-to render said operable meanseffective.

7. In a cyclically operating refrigerating system having a condenser andan evaporator, means operable to supply refrigerant medium withdrawnfrom the evaporator to the condenser, means operable intermittently toactuate said supply means, and means continuously effective to rendersaid supply means operable irrespective of said intermittent meansthereby to maintain the condenser pressure and temperature greater thanthe evaporator pressure and temperature.

8. In a refrigerating system having an evaporator, a condenser and acompressor communicatively connected together, an electric switchcontrolling operation of said compressor, means normally controllingsaid switch, and means operable in accordance with the pressure of therefrigerant medium discharged from said compressor and acting at adischarge pressure substantially below normal discharge operatingpressure to actuate said switch to start operation of said compressorirrespective of said normaliy controlling means.

9. In a refrigerating system having an evaporator, a condenser and acompressor communicatively connected together, an electric switchcontrolling operation of said compressor, means to movesaid switch toclosed position, and means operable in accordance with the pressure-o1the refrigerant medium discharged from said oompressor and opposingclosure of said switch by said switch moving means, said operable meansacting upon decrease of discharge pressure below normal dischargeoperating pressure to release said moving means to close said switch.

10. In a refrigerating system, means defining a space to be cooled, aheat transfer means located in heat transfer relation with and forcooling said space, means operable upon energization to remove heat fromsaid transfer means, means operable intermittently to energize saidoperable means so that heat is removed from said transfer means and thetemperature of said transfer means is lowered thereby to maintain saidspace within a desired temperature range, means to discharge the heatremoved from said transfer "means, and means responsive to thetemperature of said discharge means and operable automatically upon areduction of temperature of said discharge means to energize saidfirst-named operable means prior to energization thereof by saidintermittent means.

11. In a refrigerating apparatus having a space to be cooled, a heattransfer means having a predetermined range of temperature variation andlocated in heat transfer relation with and for cooling said space, meansoperable upon a temperature increase of said transfer means to the upperlimit of said range to remove heat from and to lower the temperature ofsaid transfer means to thelower limit of said predetermined rangethereby to maintain said space within a desired temperature range, andmeans operable upon a reduction of temperature of the medium surroundingsaid space to start operation of said operable means irrespective of thetemperature of said transfer means.

12. In a refrigerating system, an enclosure to be maintained within adesired temperature range .andrsubject to variations in temperature, aheat abstracting unit affected by changes in ambient temperatureexternal of said enclosure, a cooling coil located within said enclosureand operatively connected to said unit, means to start operation of saidunit at a predetermined high temperature of said coil and to stopoperation of said unit at a predetermined low temperature of saidcoil'to maintain the temperature of said cooling coil betweenpredetermined high and low temperature limits, and means renderedeffective by decrease of ambient temperature and operable upon suchdecrease to start operation of said unit.

13. In a refrigerating system, an enclosure to be maintained within adesired temperature range and located in a space subject to variationsin temperature, a refrigerant condenser located in the space andexternal of said enclosure, a

cooling coil located within said enclosure and operatively connected.to. said condenser, means to circulate refrigerant through --said coiland said condenser, means controlling said circulating means andoperable to maintain the temperature of said cooling coil betweenpredetermined high and low temperature limits, and means responsive to atemperature of said condenser lower than the desired operatingtemperature of said condenser and operable at such lower temperature tostart operation of said circulating means.

,14. ha refrigerating apparatus, an enclosure, an evaporator within saidenclosure and having a temperature range of operation, means to withdrawrefrigerant medium from said evaporator, control means for saidwithdrawing means, means operable in accordance with an increasingevaporator temperature to actuate said control means to start saidwithdrawing means, means operable upon a decrease of evaporatortemperature due to operation of said withdrawing meansto actuate saidcontrol means to stop said withdrawing means, and means operable tostart-said withdrawing means upon reduction of ambient temperaturesurrounding said withdrawing means irrespective of the operation of saidfirst-named and said second-named operable means.

WILLIAM J .HARVEY.

